Electrophoretic deposition plays a major role in many industrial coating processes. However it is observed that the usage of the standard electrophoretic deposition process with one counter electrode leads to an inhomogeneous layer thickness distribution on the workpiece. In this article it is shown by numerical methods that segmented counter-electrodes with individual potential differences can be successfully used to reduce the amount of coating material in the process. For the optimisation an efficient mathematical model with a thin layer approximation is introduced. Therein it is especially necessary to model the effect of the deposited layer on the applied electric field. So the aim of this work is on the one hand, to extend the existing models to arbitrary non-planar geometries in three space dimensions, and on the other hand to apply this model for the optimisation of industrial coating processes.